The present invention relates to an air bag housing structure, and more particularly to an air bag housing structure incorporating an extruded cushion housing for storage of an inflatable air bag cushion therein.
It is well known in the prior art to provide an air bag module which includes an inflatable air bag cushion for protection of a vehicle occupant in the event of a collision. The air bag module typically includes an inflator for discharging an inflation medium to inflate the air bag cushion upon the occurrence of a predetermined level of vehicle decelaration or other measurable condition.
The inflator and the air bag cushion are typically stored within a housing structure of substantially unitary construction. Such a housing is generally defined by opposing side walls which are joined by a bottom wall and opposing end walls to define a deep trough-like structure which is open at the top. One end wall typically includes an enlarged opening for receiving the inflator therethrough during the assembly process. The inflator is typically of a substantially cylindrical configuration including a plurality of gas discharge openings disposed about one end. The air bag cushion is typically stored in a folded condition atop the inflator within the depression existing between the walls of the housing.
Upon activation of the inflator, the air bag cushion is filled with a predetermined quantity of the inflation medium discharged by the inflator thereby causing the air bag cushion to deploy outwardly through the top opening formed by the side walls and end walls of the housing structure. The air bag cushion typically includes a means of attachment to the housing such as a retaining rod attached to the rim of the housing so as to hold the air bag cushion in place relative to the housing during the inflation process.
Initial prior art housings were formed from stamped steel which yields an enclosure of high strength. However, such a structure has the detriment of adding a relatively substantial mass to the vehicle structure and may require corrosion resistance treatment prior to installation.
In order to overcome the deficiencies of stamped steel housings, it has been proposed to utilize aluminum housings formed by plastic deformation through a deep drawing process so as to yield the desired walled construction. While such an aluminum housing formed entirely by a deep drawing process offers the potential benefits of low weight in combination with excellent corrosion resistance, the deep drawing of aluminum has inherent depth restrictions due to the naturally occurring thinning at the lower portions of the formed structure as the depth of the draw is increased.
It has also been proposed to utilize an aluminum extrusion process to form an open ended structure for housing both the air bag cushion and inflator and to thereafter attach steel or magnesium end caps to close off both ends of the housing and form the desired enclosure. Such an extruded housing of aluminum offers the benefits of low weight and controlled uniform wall thickness. However, since the structure formed by such an extrusion process will be substantially uniform along its entire length, it is difficult to accommodate a number of variations of air bag cushions and inflators within a housing formed exclusively by such an extrusion process with subsequently applied end caps. Specifically, if the inflator is shorter than the required cushion containment portion of the housing, the overall structure must undergo substantial post processing to accommodate the inflator or a relatively complex end cap design must be utilized.
It has also been proposed to utilize housings formed entirely from injection molded plastic. However, due to the wide variety of air bag cushions and inflators which are utilized, the cost and lead time for the required injection molding equipment may be prohibitive.
Finally, it has been proposed to form housings entirely from relatively lightweight die cast materials such as magnesium. However, the cost of such materials may be prohibitive.
This invention provides an advantageous containment structure for housing an inflatable air bag cushion and inflator which utilizes extrusion processes to form the portion of the containment structure which houses the inflatable cushion while utilizing non extrusion processes to form the portion of the containment structure which houses the inflator in fluid communication with the inflatable cushion. The portion of the containment structure which houses the inflatable air bag cushion is preferably formed from a lightweight, readily deformable material and will preferably be formed from extruded aluminum or plastic. The portion of the containment structure housing the inflator is preferably formed by a deep drawing or molding process so as to include an integral chamber sized for the acceptance and storage of the inflator therein. The portions of the containment structure housing the inflatable air bag cushion and the inflator may either be formed as separate elements or may be part of a unitary construction.
Advantageously, the containment structure, according to the present invention, permits the substantial utilization of aluminum or other low cost, lightweight, extrudable materials. The present invention provides the added advantage of utilizing a combination of extrusion and non-extrusion formation techniques such that the portion of the structure which houses the inflatable air bag cushion may be formed substantially by extrusion processes thereby gaining the benefit of highly efficient extrusion practices. Non-extrusion formation techniques such as deep drawing may be used in the formation of the three dimensional chamber for housing the inflator. It has been found that the combination of extrusion and non-extrusion formation practices for forming different portions of the same containment structure provides substantial synergistic benefits by permitting the utilization of lightweight materials throughout the containment structure and by permitting substantial versatility in the configuration of the chamber housing the inflator.
According to one potentially preferred aspect of the present invention, these advantages and features are accomplished by providing an air bag containment structure which includes a cushion housing formed from aluminum or plastic by the forced extrusion of such material. The cushion housing is of a depressed open-ended channel configuration having a recess between opposing side wall elements. The recess formed between the side wall element is dimensioned to accept a folded inflatable air bag cushion therewithin. End caps made of a material compatible with the material forming the cushion housing are attached across the open ends of the extruded cushion housing to form a three dimensional walled enclosure within which the air bag cushion is housed.
An inflator housing formed of a material compatible with the cushion housing and including an integral chamber of depressed profile for storage of a gas emitting inflator is connected to the cushion housing such that the gas emitting inflator is in fluid communication with the inflatable air bag cushion. The chamber of depressed profile for storage of the gas emitting inflator is formed by non extrusion formation techniques, and is preferably formed from deep drawn aluminum. The portion of the containment structure which houses the inflator may be integral with the portion housing the inflatable air bag cushion. In the event that the portion of the containment structure housing the inflator is discrete from the portion housing the inflatable air bag cushion, the inflator housing portion may include outwardly extending flange structures which cooperatively engage the open ends of the cushion housing thereby serving as end caps for the cushion housing. The air bag containment structure may be formed entirely from aluminum if desired.
Thus, it will be appreciated that the present invention provides a substantial degree of versatility in the manufacturing process thereby permitting the more efficient utilization of materials of construction and formation techniques within a wider variety of structural configurations. The present invention thereby yields a highly efficient, cost effective and lightweight containment structure for use in housing an inflatable air bag cushion and inflation element.